Having a hard time finding a suitable 1/8" cog to drill for disk mounting

Singlespeed & Fixed Gear"I still feel that variable gears are only for people over forty-five.
Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

Having a hard time finding a suitable 1/8" cog to drill for disk mounting

Having a hard time finding a suitable 1/8" cog to drill for disk mounting

Recently bought a monocog and I would like to mount a fixed cog to the unused 6 bolt iso disk mount on the rear wheel for a fixed gear option. Boone makes an amazing Ti cog that does exactly this but the time to machine and cost are prohibitive. The instructions on www.63xc.com cite using a shimano DX cog. That and every other cassette cog or driver cog I can find are 3/32". So, where can I find a 1/8" cog suitable for drilling?

I've done a convertion that way. I used a cog from an old cassette I had and drilled it. The cog was tempered steel so I had to untemper it before I could drill though it by heating it up almost red hot and then dunking it in water. Drilled through no problem after that. Of course I had ruined 2 drill bits by then. The Boone cogs look awesome for this type of convertion. Too bad I stripped some of the threads on the hub trying this before. Should have spent a bit more time paying attention to bolting steel to aluminum. Good luck.

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How about "anywhere"? Why couldn't you drill out any cog you can lay your hands on? You'll more than likely have to grind off the lip, and you probably can't use a 16T or smaller, cuz the bolt heads will contact the chain (What's the smallest cog anyone has successfully drilled yet?) Of course, if chainline requires a wider cog, it's different. BTW, I'm pretty sure you can get away with putting in a spacer if you need to.